1. Field of the Invention
The invention relates to driving apparatus utilizing flexible support means for supporting the absorber rods of nuclear reactors.
2. Description of the Prior Art
The use of flexible support members, such as cables or chains, for the lifting and lowering of absorber rods within bores in nuclear reactor cores are known in the prior art. For example, the Auslegeschrift No. 11 46 988 discloses a mechanical device including a cable winch, wherein the absorber rod is supported at the lower end of the cable, while the upper end of the cable is rigidly mounted at the winch-housing and maintained stationary. The cable is led in series several times across two roller sets, the distance between which is variable. This device does not require a bulky cable drum, the latter being undesirable in nuclear reactors because of its comparatively large overall dimension.
A cable drum for the storing of a flexible support member having a control rod supported at its free end is described in the Auslegeschrift No. 10 92 572. The drum, driven by an electric motor, is installed in a chamber that is disposed outside of the reactor pressure vessel and provided with a biological screening.
It is known from the Auslegeschrift No. 12 23 469 to guide the flexible support member around an 180.degree. turn on a guide roller, at one end of which member the control rod is hung and at the other end of which member is mounted means for storing portions of the flexible support member not needed at the moment. Below the guide roller are provided two interlocking systems for controlling the flexible member hanging down from the roller. During the simultaneous opening of both interlocking systems, the flexible support member runs across the roller and the control rod is permitted to freely fall down into the reactor core.
A further device for the insertion of absorber elements into the core of the reactor is described in the Offenlegungsschrift No. 23 32 930. This device consists of a chain for supporting the absorber rod, a chain wheel driven by a motor, and a coupling element between the absorber rod and the chain. The coupling element may be an electromagnet or a mechanical gripping device. The unused portion of the chain is stored in a chain box.
Furthermore, the Offenlegungsschrift No. 15 89 666 discloses a control device for a control rod of a nuclear reactor whose mechanism is arranged in the axis of the control rod and designed in such a way that the transport of the fuel elements is not hindered. This is achieved by means of a rotating arm. The mechanism is connected with its upper part to a driving organ and with its lower part across a detachable system for locking of the control rod. During normal operation, both parts are coupled to each other by an electromagnet.